The present invention relates to mutlipolar switches, and more particularly to improvements in multipolar switches of the class disclosed in commonly owned U.S. Pat. No. 4,410,225 to Stoewe et al.
The patented multipolar plug comprises a plate-like carrier with printed conductor tracks. If the plug is a four-pole plug, it comprises two prongs each of which carries two printed contact blades. An insert of the plug is installed in a two-piece housing and carries the contact elements. Such insert is further provided with extensions which are disposed between pairs of contact elements and are provided with latching bosses receivable in complementary latching elements of a terminal board.
A drawback of the patented plug is that the printed conductor tracks are subjected to pronounced wear in response to repeated insertion of the plug into or its withdrawal from a receptacle, such as the aforementioned terminal board. Furthermore, the conductor tracks tend to become separated from the carrier and thus prevent the establishment of reliable contact with the complementary conductors in the terminal board.
German Offenlegungsschrift No. 23 11 809 discloses a modified plug which is intended for use in the communications field. Such plug comprises a synthetic plastic body having an enlarged portion which is formed with slots, and strip-shaped metallic contact members which are inserted into the slots. The end portions of the contact members are bent along arcs of 180 degrees and extend into complementary grooves at the ends of the respective prongs. Those portions of the contact members which are adjacent to the enlarged portion of the plastic body are bent outwardly in order to properly engage the complementary contact elements. Male latching elements on the contact members extend into complementary female latching elements of the plastic body adjacent to the enlarged portion. The just described plug exhibits the advantage that it need not be provided with a discrete housing. However, the plug is rather expensive because the contact members must be machined and shaped in a series of successive operations.
German Auslegeschrift No. 11 35 541 discloses a plug wherein portions of the contact members are embedded in a carrier of insulating synthetic plastic material. Bare ends of the contact members extend from the carrier and can be inserted into the slots of a receptacle by using the carrier as a handle.